JPS5935937B2 - water-based paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-soluble or water-dispersible coating composition having excellent crosslinking and anticorrosion properties.

It has been well known that materials having unsaturated bonds in their molecules, such as natural drying oils or drying oil fatty acids, synthetic resins modified with these (e.g. epoxy resins, alkyd resins, etc.), and diene polymers, can be used as paint vehicles. It is being
In addition, water-based paints obtained by neutralizing polycarboxylic acid resins with large amounts of carboxyl groups introduced into the above-mentioned materials with bases are generally used as primers whose main function is to prevent base metals from corrosion. This is also known.
Usually, a hexavalent chromium compound such as strontium chromate is added to the paint used as the primer in order to improve anticorrosion ability, that is, corrosion resistance. However, this hexavalent chromium compound is primarily a toxic substance, and its use is being restricted from the viewpoint of environmental hygiene and pollution prevention. Furthermore, if this hexavalent chromium compound is used in an amount sufficient to exhibit sufficient anticorrosion performance, the oxidizing effect of its acid tends to oxidize unsaturated bonds in the paint resin and deteriorate the crosslinking properties of the paint. . This is remarkable in water-based paints, especially electrodeposition paints. Another known method for improving the anticorrosion performance of paints is to add a phenol resin. However, since this phenolic resin generally has reducing properties, when it is used in combination with an unsaturated polycarbonate resin, the crosslinking or curing properties of this resin are inhibited, and the resulting paint requires baking at high temperatures. Become. Furthermore, when a phenolic resin is added to a relatively low-molecular and soft polycarboxylic acid resin such as maleated oil, tackiness remains on the coating surface even after baking at high temperatures, resulting in a strong coating. is difficult to obtain, making it difficult to put it into practical use. The present invention aims to provide a new coating composition that eliminates all the drawbacks of coating compositions containing polycarboxylic acid resins having unsaturated bonds and phenolic resins, and provides a tough coating film with excellent corrosion resistance. It was made for the purpose of providing. That is, the present invention provides: 1. 100 parts by weight of at least one oxidatively polymerizable or thermally polymerizable unsaturated polycarboxylic acid resin selected from maleated drying oil, maleated epoxy ester resin, and maleated polybutadiene resin, 2. 1 to 50 parts by weight of a phenol formaldehyde condensation product having at least one methylol group to the above 1, and 3 to 0.001 to 50 parts by weight based on the above 1 in an aqueous liquid containing the above 1 and 2. The present invention relates to an aqueous coating composition, characterized in that it contains at least one part of dissolved organic and/or inorganic copper compounds, such that 5 parts by weight of dissolved metallic copper are present.

The composition of the present invention has excellent crosslinking properties and forms a tough coating film, and this coating film exhibits remarkable corrosion resistance.

This effect is truly surprising considering that both phenolic resins and copper compounds, when used alone, generally have the effect of suppressing the curing of polycarboxylic acid resins having unsaturated bonds or thermal polymerization accompanied by oxidation. It is. The oxidatively polymerizable or thermally polymerizable unsaturated polycarboxylic acid resin used in the present invention mainly has oxidatively polymerizable or thermally polymerizable unsaturated bonds in its crosslinking, and is usually used as a resin for electrodeposition coatings. You can use what is currently available.

In the present invention, at least one oxidatively polymerizable or thermally polymerizable unsaturated polycarboxylic acid resin selected from maleated drying oil, maleated epoxy ester resin, and maleated polybutadiene resin is used. Incidentally, as the drying oil, any of natural oils, synthetic oils, and processed oils can be used. In the present invention, these polycarboxylic acid resins have an iodine value of 60 or more and an acid value of 30.
Those having the above can be preferably used. Furthermore, it is also possible to use a conventionally known crosslinking agent in combination with the polycarboxylic acid resin, if necessary. Examples of the phenol-formaldehyde condensation product having at least one methylol group in the molecule used in the present invention include carbolic acid, cresol, p-tert-butylphenol, p-butylphenol, p-phenylphenol, etc. Examples include condensation products of phenols with or without a substituent at the para or ortho position and formaldehyde, and condensation products of divalent phenols such as bisphenol A and formaldehyde.

It is important that these condensation products have at least one methylol group in their molecule; if they do not have a methylol group, they will have poor storage stability when used in an aqueous coating bath. The amount of the above-mentioned phenol-formaldehyde condensation product added to the above-mentioned polycarboxylic acid resin is not particularly limited. It is blended in an amount of 1 to 50 parts by weight per 100 parts by weight. If too much is added, the water dispersibility of a water-based paint tends to decrease. The aqueous coating composition of the present invention must also contain an organic and/or inorganic copper compound, at least a portion of which is dissolved in the aqueous liquid.

These copper compounds include, for example, copper naphthenate, copper stearate,
It can be contained in the aqueous liquid in the form of a copper salt of a fatty acid such as copper oleate, or in the form of a copper salt of the polycarboxylic acid resin described above. Furthermore, copper hydroxide,
It can be present in the aqueous liquid as an inorganic copper compound such as copper oxide or basic copper carbonate. When using a water-insoluble copper compound such as copper oxide or basic copper carbonate, the copper compound may be reacted with the above-mentioned polycarboxylic acid resin by heating or reacted with another solubilizing agent such as carboxylic acid. After that, it may be incorporated into an aqueous liquid. As the above-mentioned copper compound in the present invention, copper salts of mineral acids such as copper chloride and copper sulfate can also be used, but especially when the aqueous coating composition obtained by the present invention is used for electrodeposition coating. This is not preferred because the presence of mineral acids may have an adverse effect on the finished state of the resulting coating film. The above-mentioned copper compound in the present invention contains 0.001 to 5 parts by weight (preferably 0.005 parts by weight, preferably 0.005 parts by weight) of metallic copper, which is usually dissolved in an aqueous liquid, based on 100 parts by weight of the polycarboxylic acid resin in the aqueous liquid. ~3 parts by weight). The composition containing the polycarboxylic acid resin, phenol-formaldehyde condensation product, and copper compound of the present invention is neutralized with a base in a conventional manner to form a water-based paint.

Here, as the base, known bases used in ordinary water-based paints and electrodeposition paints are used. Examples include alkali hydroxide, ammonia, and organic amines. The aqueous coating composition of the present invention can be applied satisfactorily by ordinary coating methods such as dip coating, spray coating, and brush coating, and exhibits excellent performance.

Especially when used for electrodeposition coating, even more excellent performance is exhibited. When the aqueous coating composition of the present invention is used as a primer, coloring pigments such as titanium white, carbon black, and red iron, and extender pigments such as silica and talc can be added to the composition. The present invention will be explained below with reference to Examples. In each example, "%" or "%" indicates part by weight or % by weight.

Example 1 588 parts of maleic anhydride and 0.03 parts of xylene are added to 2,640 parts of linseed oil and reacted at 200° C. in a nitrogen stream.

The reaction was allowed to proceed at this temperature until free maleic acid was reduced to 0.1% or less, then cooled to 120°C and ethanol 2
50 parts were added thereto, and the mixture was further reacted at 120° C. for 1 hour and 30 minutes to obtain a half-esterified product. 30 parts of copper hydroxide was added to 1000 parts of the obtained half-esterified maleated linseed oil, and 1
The mixture was heated and mixed at 00°C for 2 hours.

The reaction product was a dark green, homogeneous, viscous resinous material. 8
After cooling to 0°C, the mixture was diluted with 370 parts of ethylene glycol monoethyl ether to a solid content of 70q17.

Next, 143 parts of a 70% monomethylolated phenolic resin (trade name WP-71, manufactured by Gunei Chemical Industry Co., Ltd.) was mixed at room temperature, and 105 parts of trinitylamine and 1438 parts of deionized water were mixed.
The mixture was stirred at room temperature to obtain an aqueous varnish with a resin solid content of 35%. Comparative Example 1 Half-esterified maleated linseed oil of Example 1 100
357 parts of ethylene glycol monoethyl ether was added to 0 parts to dilute the solid content to 70%.

Next, at room temperature, 105 parts of triethylamine and 12 parts of deionized water were added.
52 parts were added and stirred at room temperature to obtain an aqueous varnish with a resin solid content of 35%. Comparative Example 2 Half-esterified maleated linseed oil of Example 1 100
Add 357 parts of ethylene glycol monoethyl ether to 0 parts, add 143 parts of 70% monomethylolated phenolic resin at room temperature, stir at room temperature, then add 105 parts of triethylamine and 1395 parts of deionized water and stir at room temperature to solidify the resin. An aqueous varnish with a content of 35% was obtained.

Comparative Example 3 Half-esterified maleated linseed oil of Example 1 100
30 parts of copper hydroxide was added to 0 parts, and the mixture was heated and mixed at 100° C. for 2 hours.

After cooling to 80° C., the mixture was diluted with 370 parts of ethylene glycol monoethyl ether to a solid content of 70%.

105 parts of triethylamine and 1 part of deionized water at room temperature after cooling.
Add 295 parts and stir at room temperature until the resin solids content is 35%.
A water-based varnish was obtained.

Each of the aqueous varnishes obtained from Example 1 and Comparative Examples 1, 2, and 3 was diluted with deionized water to a solid content of 10% to prepare an electrodeposition paint bath. and specific conductivity were measured.

Next, two lead phosphate treated plates of the same size ("Bonderite #37 treated mild steel plates" manufactured by Nihon Parkerizing Co., Ltd.) were placed in these baths so that the distance between the plates was 15 cfrL, and the plate ratio was 1:1. The area was 2 decimeters, the current was applied for 2 minutes, and the power source was three-phase full-wave rectification.The electrodeposition coating was performed by applying electricity to a film thickness of 25μ under the conditions of a three-phase full-wave rectification, washing with water, and heating at 170°C for 30 minutes to obtain a test plate. . The coated surface condition, hardness, and corrosion resistance of the obtained test plate were measured according to the following. The results are shown in Table 1. Coated surface condition: The smoothness, repellency, dirt, etc. of the electrodeposition coating film surface of the test plate were observed with the naked eye and evaluated as shown below.

◎It is smooth and has no coating defects.

○ Slightly inferior smoothness.

△Lack of smoothness and a uniform coating film cannot be obtained.

Pencil hardness: Measured according to JIS-K54OO.

Corrosion resistance: Cut diagonally into the soil of the test plate with a knife so as to reach the base material, and place this in a salt spray tester containing 5% saline at a temperature of 35°C.
m7! The time required to reach L was measured.

As shown in Table 1, the water-based coating composition of the present invention exhibits excellent corrosion resistance in anodic electrodeposition, and is made using only a known polycarboxylic acid resin (Comparative Example 1) or a mixture thereof with a phenolic resin (Comparative Example 2). ), or one in which a copper compound was simply reacted with a polycarboxylic acid resin (Comparative Example 3), it can be seen that the corrosion resistance is extremely superior.

Example 2 2105 parts of linseed oil fatty acid and “Epicote #828” (
1781 parts of an esterified product obtained by reacting 752 parts of epoxy resin manufactured by Shell Petrochemical Co., Ltd., 446 parts of maleic anhydride, and 20 wt1 of xylene! , and proceeded with the reaction at 200°C in a nitrogen stream until free maleic anhydride was reduced to 0.1% or less. After cooling to 140°C, 180 parts of n-butanol was added and reacted at 140°C for 1 hour to form a half-esterified product. I got it.

After cooling to 100°C, the mixture was diluted with 893 parts of ethylene glycol monoethyl ether to a solid content of 70%.

At room temperature, 10 parts of a xylene solution of copper naphthenate (metallic copper content: 5%) was added to 1430 parts of the above maleated epoxy ester half-ester and mixed, followed by 143 parts of 70% dimethylolated bisphenol A (rayal resin). 145 parts of a 40" potassium hydroxide aqueous solution and 9 parts of deionized water
28 parts were added and stirred at room temperature to obtain an aqueous varnish with a solid content of 40%.

Comparative Example 4 To 1430 parts of a 70% ethylene glycol monobutyl ether solution of the maleated epoxy ester half-ester obtained in Example 2, 145 parts of a 40q6 potassium hydroxide aqueous solution and 1060 parts of deionized water were added at room temperature and stirred to form a solid. A 40% aqueous varnish was obtained.

Comparative Example 5 1430 parts of a 70% ethylene glycol monobutyl ether solution of the maleated epoxy ester half-ester obtained in Example 2 was mixed with 43 parts of 70% dimethylolated bisphael Al at room temperature, and deionized with 145 parts of a 40q6 potassium hydroxide aqueous solution. Add 1178 parts of water and stir.
An aqueous varnish with a solid content of 40% was obtained.

Comparative Example 6 To 1430 parts of a 70% ethylene glycol monobutyl ether solution of the maleated epoxy ester half-ester obtained in Example 2, 1 part of a xylene solution of copper naphthenate was added at room temperature.
After adding and mixing 0 parts (metallic copper content 5%), 145 parts of 40
% potassium hydroxide aqueous solution and 1127 parts of deionized water were added and stirred to obtain an aqueous varnish with a solid content of 40%.

Electrodeposition paint baths were prepared using each of the aqueous paint compositions obtained in Example 2 and Comparative Examples 4, 5, and 6, and their properties were tested.

The test method and sample preparation were the same as in Example 1. The results are shown in Table 2 below.

As shown in Table 2, it is clear that the aqueous coating composition of the present invention (Example 2) provides excellent corrosion resistance.

Example 3 112 parts of diethanolamine was added to 1430 parts of a 70% ethylene glycol monoethyl ether solution of the maleated epoxy ester half-ester obtained in Example 2,
Add 958 parts of deionized water and stir at room temperature until the solid content is 40.
A q17 aqueous varnish was obtained.

100 parts of this 40q6 water-based varnish, 25 parts of titanium white,
1 part carbon black, 0.2 parts copper hydroxide and 0
．． Two parts of copper oxide were added and dispersed in a Pall mill for 20 hours.

126.5 parts of the above dispersion were mixed with 150 parts of the above 40% aqueous varnish and 10 parts of 70% monomethylolated p-tert-butylphenol, stirred at room temperature for 30 minutes, and then diluted to 10% with deionized water. A water-based paint composition of the present invention was prepared.

Example 4 1,2-polybutadiene (molecular weight 12
00,1,2 vinyl bond 89%, trans 1,4 bond 1
1%), 32 parts of maleic anhydride and 2 parts of xylene were added, and the free maleic acid was reduced to 0 at 200°C in a nitrogen stream.
．． The reaction was allowed to proceed until the concentration decreased to below 1%.

After cooling to 140°C, add 20 parts of n-butanol 14
The reaction was carried out at 0°C for 1 hour. After cooling to 100°C, ethylene glycol monoethyl ether was added so that the resin content was 70%. 70% resin solution 1 thus obtained
00 parts, 8 parts of triethylamine and 126 parts of distilled water were added to obtain a water-dispersed resin liquid having a resin content of 30%.

30 parts of iron oxide and 1 part of carbon black were added to 100 parts of this 30% water-dispersed resin solution and dispersed in a ball mill for 20 hours.

To 100 parts of the above dispersion, 200 parts of the 30% above water-dispersed resin solution
1 part and 30 parts of a 70% ethylene glycol monobutyl ether solution of the reaction product of the half-esterified maleated linseed oil obtained in Example 1 and copper hydroxide, and further 10 parts.
Add 3 parts of monomethylolated phenolic resin and stir at room temperature.
After stirring for 0 minutes, the mixture was diluted to 12% with deionized water to obtain an aqueous coating composition of the present invention.

Practical example 5 1,2-polybutadienecarboxylic acid (molecular weight 1450,
1,2-bond 85%, transformer 1,4-bond 15%) 1
100 parts of maleic anhydride and 100 parts of xylene were added to 00 parts, and the mixture was reacted at 150°C in a nitrogen stream for 15 hours, and then the solvent was distilled off at 100°C under reduced pressure.

To this maleate, 5.5 parts of distilled water and 0.1 part of triethylamine were added and reacted at 100°C for 1 hour, then 150 parts of distilled water was added and mixed with a stirrer, and the mixture was allowed to stand for 3 hours to cause phase separation. was removed to remove unreacted maleic anhydride. Ethylene glycol monoethyl ether was added to the reaction product thus obtained so that the resin content was 70%.

Next, 10 parts of triethylamine was added to 100 parts of this resin solution.
1 part and 123 parts of distilled water were added to obtain a water-dispersed resin liquid having a resin content of 30%.

An aqueous coating composition of the present invention was prepared in the same manner as in Example 4 using this water-dispersed resin liquid. The water-based paints obtained in Examples 3, 4 and 5 were electrodeposited under the same conditions as in Example 1.

The test results are shown in Table 3 below. The coated plate was treated with Bonderite #37.

It can be seen that even better corrosion resistance can be obtained when the pigment is dispersed as in Examples 3, 4 and 5.

Claims (1)

[Claims] 1 (1) 100 parts by weight of at least one oxidatively polymerizable or thermally polymerizable unsaturated polycarboxylic acid resin selected from maleated drying oil, maleated epoxy ester resin, and maleated polybutadiene resin, (2) in the molecule In an aqueous liquid containing 1 to 50 parts by weight of a phenol formaldehyde condensation product having at least one methylol group based on the above (1) and (3) the above (1) and (2), the above A water-based paint characterized by containing an organic and/or inorganic copper compound in which at least 1 part is dissolved so that 0.001 to 5 parts by weight of dissolved metallic copper is present based on (1) Composition.